Strapping machine



Feb. 19, 1957 M. M. EISENBERG 2,781,516

STRAPPING MACHINE Filed Aug. 27. 1954 4 sheets-sheet 1 INVENTOR Monms M.ElsENBERe ATTORNEES' Feb. 19, 1957 M, M E|SENBERG 2,781,516

STRAPPING MACHINE Filed Aug. 27, 1954 4 Sheets-Sheet 3 3a f6 f4 F-.

/36 H4 I #70 ,4 7 I INVENTOR MoRRls M ElsENBERG- United States Patent O"ice ,i

STRAPPING MACHINE Morris M. Eisenberg, Clarence, Mo.

Application August 27, 1954, Serial No. 452,556

8 Claims. (Cl. 1-123) This invention relates to a machine for strappingboxes and more particularly to a machine for automatically applying andnailing metal strapping to a box.

The art of applying metal strapping to boxes, particularly the ends or"boxes, is extremely old and has been the subject of rather extensivedevelopmental work. Numerous rather complex machines have been devisedfor automatically applying strapping and then sealing such strappingprimarily by means of some type of clip, seal or tie which securelyclamps together the overlapped ends of the strap independently of thebox itself. Other machines utilize wire binders rather than metalstrapping and provide tying means for forming various types of twists orties in the wire to secure the ends together.

Still other machines were designed for nailing metal strapping aroundthe ends of boxes, but these machines utilized the nails not so much tofasten the overlapped ends of the strapping together as to fasten thestrapping to the boxes on all sides thereof. No provision was made forautomatically feeding the strapping completely around 'the box and theentire operation was manual in the sense that the operator had to placethe box on one edge, actuate the nailing mechanism, turn the box to asecond edge, actuate the nailing mechanism, and so on until the operatorcompletely rotated the box and nailed strapping to each edge thereof.

The previously available machines were all developed for a specificpredetermined job and utilized a large amount of rather complexmachinery. Conventional electric motors ere used almost universally fordriving the machine and a large number of driving wheels were utilizedfor feeding and then withdrawing and tensioning the strap. The use ofthis type of motive power and strap drive required the use of numerousclutches of various types in the tension mechanism, while the use ot'seals, clips and ties for securing the strap necessitated thedevelopment of rather complicated clamping or holding mechanisms forretaining the loose end of the strap during the tensioning operation.

ln tne usual prior art machine the source of motive power, usually anelectric motor, operated continuously while the machine was in use, withfeed of the trap being controlled either by clutches or by movement ofthe strap driving wheel, and with tensioning of the strap taking placethrough a clutch. In addition those machines which did provide forautomatically feeding the strapping entirely around the box utilizedstrapping guides with gaps therein at the position of sealing mechanismand because of such construction necessarily employed rather complexstrap guiding means at such gap. Most controls were of the cam typewhich necessarily had to be designed into the original machine.

According to the present invention there is provided a simple andinexpensive means for converting a standard nailing machine into amachine for applying and nailing strapping to boxes. A continuousunbroken strap guide is utilized in conjunction with a reversible sourceof motive power which may be stalled without any deleterious 2,781,516Patented Feb. 19, 1957 eects and without excessive consumption of power.This combination makes it possible to eliminate the complicated andcomplex multi-wheel drive and clutching arrangements of previousmachines and makes possible a simple and inexpensive guide means for thestrapping.

According to the invention the strap is fed completely about the box,the free end thereof is held by an extremely simple holding mechanism,the strap is tensioned and then nailed at the overlapped portion only inan entirely automatic sequence. Complicated strap tensioningarrangements are avoided and the operating table and nailing mechanismare provided by the existent standard nailing machine.

It is accordingly a primary object of the present invention to provide asimple and inexpensive machine for applying strapping around a box andfor nailing the overlapping portions of such strapping to the box.

It is another object of this invention to provi-de such a strappingmeans by modifying a standard nailing inachine.

lt is another object of this invention to provide a means for feedingstrap around a box and then tensioning such strap by means of the sameprime mover, which may be stalled without -damage thereto and withoutexcessive power consumption.

It is another object of this invention to provide a method and means forapplying and nailing strapping to boxes utilizing a continuous strappingguide which completely encircles the box to be strapped.

It is another object of thisy invention to provide a means and methodfor applying and nailing strapping to a box utilizing a simplifiedplunger type holding mechanism for the strap tensioning operation.

Further objects and advantages of the invention will become apparentupon reference to the following specification, claims and drawingswherein:

Figure 1 is a side elevational view, partly in section, of a' strappingand nailing machine according to this invention;

Figure 2 is another side elevational view, partly in section, of thestrapping and nailing machine of Figure 1;

Figure 3 is a horizontal section taken on the line 3 3 of Figure l;

Figure 4 is a detailed sectional view of the tape cutting mechanism;

Figure 5 is a cross section of the cutting knife and anvil of Figure 4;

Figure 6 is a detailed plan View partly in section of the finger strapguide control means;

Figure 7 is a side elevation of the finger strap guide Y control meansof Figure 6;

Figure 8 is a detailed elevation partly in section of the hold rdown pinassembly;

Figure 9 is a detailed view, partly in section, of the means ofattachment of the hold down pin actuating air cylinder;

A .Figure l0 is a detail view, partly in section, of one of the controlsfor the motors; and

Figure 11 is a diagrammatic View of the wiring of the various controlsin the device.

The strapping and nailing machine of this invention is assembled bymodifying a standard nailing machine such as, for example, the typeshown in the patent to Paxton, Fatent No. 2,232,725, issued February 25,1941, and consequently the drawings do not show welll known details ofthe nailing machine. Detailed information on such machines may beobtained by reference to the aforementioned patent or to other similarpatents.

Turning more particularly to the drawings there is shown in Figure 1 aAconventional nailing .machine 10 having a box or work feed conveyor 12,work table 14 and work removal conveyor 16. The work table is providedwith a pair of work ejection conveyor chains 18 and 20 for removing thecompleted Work from the table and is also provided with a pair of workstop arms 22 `and 24. These arms 22 and 24 are pivoted at the points 26and 28 and will swing freely toward the operator and the incoming box,but will move in the opposite direction with the box only to apredetermined point whereupon the arm 22 actuates a lever 30 tomomentarily depress a microswitch 32.

The arms are prevented from moving further by means of a conventionallocking mechanism on the nailing machine which releases upon the impactof the nailing operation to allow the swinging arms 22 and 24 to releasethe box. The arms are spring urged towards the work table by means ofsuitable springs such as springs 36 and 38. The pivots 26 and 28, thelever 30, the microswitch 32, and the springs 36 and 38 are supported onand fastened to a pair of supports carried by the table 14, such as T-sections 40 and 42, best seen in Figure 2. The support 42 is furtherprovided with an off-set bracket 44 for receiving the lever 30, whileone end of each of the supports 40 and 42 is also provided with a collar46 and 47 for supporting the swinging arms 22 and 24.

According to the invention the table 14 is raised by means of a pair ofair cylinders 48 and 50, best seen in Figure 2, which are supplied withair through conduits 52 and 54 which are connected to a solenoidactuated valve 56. The cylinders 48 and 50 are provided with pistons 58and 60 which are fastened to a supporting beam 62 which extendstransversely of and supports the table 14. Upon energization of theproper winding of the solenoid 56 air pressure is admitted to thecylinders 48 and and the table 14 is raised.

As the table 14 rises it actuates several control mechanisms as follows.Thus a depending bracket 64, best seen in Figure 1, is attached to atriangular brace 66 on the bottom portion of the table 14. The bracket64 carries an actuating rod 68 perpendicular thereto, see Figure 2, andthis rod engages the actuating Iever 70 of an air valve 72. Theactuating lever 70 is pivoted to the valve 72 by means of a pair of arms74 and a pivot pin 76 and is urged upwardly against the bar 68 by meansof a spring 78. The valve 72 is provided with an air inlet conduit andoutlet conduit 82, the inlet conduit being connected to a supply ofcompressed air and the outlet being connected to the hold down pinactuating cylinder to be presently described.

The depending bracket 64 is also provided on one side thereof with anodule 84 which momentarily depresses a lever 85 pivoted at 87 todepress the actuating button 86 on a microswitch 88.

The other under side of the table 14 is provided with a second dependingbracket 90 which is attached to a triangular brace 92. The bracket 90 isprovided with an elongated flat cam 94, Figures l and 2, which depressesthe actuating buttons on three microswitches 96, 98 and 100 as the tablerises. The lower end of the bracket 90 also depresses the actuatingbutton of a further microswitch 102 as long as the table is in a loweredposition.

It will thus be seen that as the table 14 rises the air valve 72 isopened to provide a supply of air to the hold down pin operatingcylinder, the microswitch 102 is opened, the microswitches 96, 98 and100 are closed, but the microswitch 88 is not -aiected inasmuch as lever85 is raised up and away from microswitch 88 by nodule 84. Microswitch88 thus remains open.

The conventional nailing machines to which the device of this inventionmay be attached are normally `provided with a pair of transverse supportbeams 104 and 106 and four vertical support elements 108, 110, 112 and afourth that cannot be seen in the drawings. These vertical elements inturn support a further pair of horizontal beams 114 and 116.

According to the invention a pair of continuous closed path strappingguides 118 and 120 are adjustably susof brackets 122 and 124 and bolts126 and 128. The bolts 126 and 128 are received in elongated holes whichrun lengthwise of the beams 114 and 116, and thus the continuousstrapping guides 118 and 120 may be moved towards and away from eachother to accommodate any size of box desired or any strapping spacingdesired.

The strapping guides are further braced by means of spacing rods 130 and132 which pass through L-shaped brackets 134, 136, 138 and 140 which aresecured to the strapping guides by any suitable means such as bywelding. A pair of lock nuts 142 and 144 provides for adjustablefastening of the rods 130 and 132 in the brackets 134, 136, 138 and 140.

The strapping guides are provided with a plurality of resilient boxguide fingers which extend both inwardly and outwardly thereof formaintaining the boxes in the proper position. Thus, referring to Figuresl and 3, the strapping guide 118 has :attached inwardly thereof boxguide ngers 146 and 148 and has attached outwardly thereof box guidefinger 150. The other strapping guide 120 has box guide fingers 152 and154 attached inwardly thereof and guide finger 156 extending outwardlythereof.

Referring more particularly to Figures 2, 3 and 4, it will be seen thatthe continuous strapping guide consists of a fiat rigid strip 158 as anupper portion, and of an arcuate strip 160 joining the ends of the strip158 to form a closed lower portion. The lower portion is subdivided intoa pair of three sided vertical channels 162 and 164 and ahorizontalchannel 166. These channels are formed by fastening, as bywelding, guide plates 168 and 170 to the rising portions of the arcuatestrip 160 and by fastening similar plates 172 and 174 to the lowermostportion of the arcuate strip 160, as may be seen in Figure 3.

The upper strip 15S has a series of apertures therein for receiving thenails, the strap, an actuating lever, and the hold down pin. Thusreferring to Figure 4 the upper strip 158 is shown as having a pluralityof holes 176 and 178 for receiving the nails and a plurality ofconventional nailing chucks 180, 182, 184 and 186 are mounted directlyover the strip 158. Each nailing chuck is provided with a conventionalnailing punch 188 and with a conventional tiexible tube 190 whichextends upwardly to the nail receiving tunnels which are not shown.

The nail punches 188 are actuated by means of a plurality of naildriving beams 192, 194, 196 and 198 which are attached to areciprocating cross head 200, as is best seen in Figure 2. The crosshead 200 is slidably mounted on the upper ends of the side standards ofthe nailing machine in vertical slots in a conventional manner asdescribed in the afore cited Paxton patent.

Referring again to Figure 4 it will be seen that approximately mid-wayin the upper strip 158 there is provided an elongated aperture 202adjacent which there is mounted an anvil block 204 having a strap feedaperture 206 therethrough. Attached to the anvil block 204 and matingwith the aperture 206 is a strap guide conduit 208 which extendsvertically upwardly and then horizontally to guide the strap through theaperture 206 in the anvil block 204 and thence through the aperture 202in the upper strip 158. As the strap 210 passes through these twoapertures it strikes the finger strap guide 212 which extendshorizontally into its path in a slightly cocked position. As the strapis fed to the left of aperture 202 in Figure 4 it is guided toward thevertical section 162 of the continuous strapping guide by means of asimilar finger strap guide 214. The strap then follows the inside of thearcuate strip 160 and emerges from vertical section 164 to again strikethe under surface of the top strip 158.

A further nger strap guide 216 guides the end of the strap into a strapcontrol lever 218 which extends through an aperture 220 in the top strip158. The strap control lever 218 is pivoted at 222 to the upper surfaceof the top strip 1,58 and its upper end engages the control button on amicroswitch 224 which is operative to stop the feed of strap. As will beexplained in more detail hereinafter the end of the tape 210 drifts pastthe strap control lever 213 after the tape feed is cut off to secure thedesired overlap.

The top strip 158 is also provided with an aperture 226 for receivnigthe hold down pin 228. The hold down pin 22-3 passes through a sleeve233 which is secured to the strip 158 in any suitable manner, such aswelding, and the pin 226 is urged upwardly by mean-s of a spring 232which reacts against the top of the sleeve 23S and against the undersideof a head 234 on the pin 228. The hold down pin 223 is depressed as thebox is raised by the table 14 in a manner presently to be explained andurges the free end of the strap 210 downwardly into engagement with thetop of the box to permit tensioning of the strap.

The anvil block 204 to which the strap guide conduit 23S is attached hasin its exposed side a vertical slot 236 having inwardly angled sidewalls 23S and 240 as is best seen in Figure 5. A guillotine type knife242 is received in the slot 236 and is held therein by means of theangled sides 23S and 240. The knife 242 is attached by means of a bolt244 to an actuating rod 246 which is supported in three aperturedbrackets 24S, 250 and 252 which are carried by the vertical portion ofthe strap lguide conduit 26S. A tension spring 254 is attached to thetop of the rod 246 and is suspended from a support bar 256 which passesover the beams 104 and 106 of the nailing machine to maintain theguillotine knife in a normally raised condition. The rod 246 is furtherprovided with a collar 253 which is locked thereon by means of a setscrew 260. Engageable with the collar S is a stud 262 which is fastenedby any suitable means, such as by welding, to the nailing beam 194.

It will be apparent from reference to Figure 4 that when the nailingbeam 194 strikes downwardly in its normal nailing operation the stud 262will force the collar 253, bar 246 and guillotine knife 242 sharplydownwardly to shear the strap 210 at the anvil block 204. The positionof the collar 258 with respect to the stud 262 is so adjusted that theknife severs the strap passing through the anvil block 204 but does notsever the strap below the strip 158. Thus the knife 242 never touchesthe surface of the box to be stopped.

After the nailing beam 194 has completed its downward stroke and rises,the stud 262 strikes a second collar 263, which is secured to the rod246 by means of a set screw 265, and forces the rod 246 and knife 242sharply upward. The knife is then retained in this raised position bymeans of the spring 254. The strap 210 is thus cut during the nailingstroke, while it is under tension, and the power to the motors isremoved substantially simultaneously.

According to the invention the prime movers for feeding the strap 210preferably consist of a pair of air i of input pipes 280, 281 and 232,233 which in turn are connected to a pair of solenoid actuated valves284 and 286. One input pipe on each air motor is adapted to run it in aforward direction while the other input pipe is adapted to run it in areverse direction under the control of the solenoid actuated valves 284and 236. The valves 284 and 286 are serially connected to a pair ofpressure regulators 288 and 290, an air oiler 292, an air filter 294 anda main valve 296 which leads to the 'source of compressed air supply.

The air motors 264. and 266 have air exhaust pipes 298 and 300 andshafts 302 and 304. The shafts 302 and 304 are connected by means ofcouplings 306 and 308 and stud shafts 310 and 312 to a pair of tapedrive wheels 314, best seen in Figure 2. The stud shafts 310 and 312 aresupported on brackets 316 and 318 by means of bearings 320 and 322. Thedrive wheels 314, as seen in Figure 2, may be knurled wheels whichengage with an idler wheel 324 which may be spring urged toward thedrive wheels. The strapping is then frictionally driven between the twowheels.

The strapping guide conduit 208 terminates a short distance from thedrive wheel 314. The `.strap is supplied from a suitable strapping reel328 pivoted at 330 and passes beneath a suitable slack remover 325,which may 332 conveniently constitute a Weighted bar 326 pivoted at 332.

When the air motors 264 and 266 are energized to feed forwardly, thestrap 210 is fed from the reel 328 into the strapping guide conduit 208,through the anvil block aperture 206, through the upper strip aperture202, over nger strap guides 212, 214, through the arcuate portion of thecontinuous 'strapping guide, under the hold down pin 223, over thefinger strap guide 216, into the lever 218, and thence beneath the bightof the tape a1- ready in the continuous strapping guide to form theoverlap.

The hold down pin 228 is actuated by means of an air cylinder 331 whichis fastened by means of a Z-shaped bracket 333 to the strapping conduit203 as may best be seen in Figures 8 and 9. Referring particularly toFigure 8 it will be seen that the head 234 of the hold down pin 228 isengaged by the underside of a lever 334 which is pivoted on a pair ofbrackets 336 carried on a support bar 338 bolted to the verticalbrackets 122 and 124. It will be obvious that when the air cylinder 331has air pressure applied thereto its piston 340 will force the lever 334downwardly and will thus depress the hold down pin 223 so that its lowerextremity passes through the aperture 226 in the strip 158 to enter thecontinuous strapping guide.

Referring to Figures 6, 7 and 8 it will be seen that the finger strapguides comprise a series of fingers 212, 214, 216, 217 and 219 on abacking bar 342. The finger strap guides 212, 214, 216, 217 and 219 passthrough suitable slots 243 in a pair of support bars 245 which arecarried by the upper strips 15S- as may best be seen in Figures 6 and 8.The backing bars 342 have levers 346 and 348 pivoted at opposite endsthereof and the ends of the levers 346 and 343 are joined at commonpivots 350 and 352 which are carried by a longitudinal bar 354.

An upwardly extending bracket 356 is carried by the longitudinal bar 354and has secured thereto by means of lock nuts 358 and 360 the piston 362of a iinger strap guide actuating cylinder 364. The piston 362 is urgedoutwardly by means of a spring 363. The actuating cylinder 364 iscontrolled by means of a solenoid actuated valve 366 and is suspended bymeans of brackets 367 from a beam 368 fastened to the beams 114 and 116.A pair of microswitches 376 and 372 is provided on the beam 363 andthese are so arranged as to be engaged by the upper portion of thebracket 356 when the piston 362 is in its extended and return positionsrespectively. By reference to Figure 6 it will be seen when the piston362 is in its extended position the finger strap guides 212,

214, 216, 217 and 219 are in their retracted positions while, when thepiston 362 is in its return position, the finger strap guides are intheir extended or inserted position.

As may be seen in Figures l and 2, the cross head 209 actuates a pair ofmicroswitches 374 and 376 on its downward or nailing stroke. Thus themicroswitch 374 is mounted on the support element 108, Figure 1, whilethe microswitch 376 is mounted on the support element 112.

As may be seen in Figure 10, the microswitch 376 is actuated by means ofa lever 378which is pivoted at 380 to a bracket 382 fastened to thesupport element 112. A coil spring 384 urges the lever 378 into tightfrictional engagement with the washer 379 so that considerable force isneeded to move lever 378. The lever thus remains in either an upward ordownward position until it is acted upon by some external means as ispresently described.

A nodule or stud 386 is provided on the cross head 261) for urging theleft end of lever 378 downwardly at the bottom of the nailing stroke.This downward movement of the left end of lever 378 opens themicroswitch 376 to cut the air supply to the air motors 264 and 266 in amanner presently to be described. Microswitch 376 is later reclosed bymeans of a retaining bar 388 which slidably passes through the table 14and terminates in a bent over portion 394. The upper end of theretaining bar 388 terminates in a bent over portion 390 which passesthrough the lever 378.

As long as the cross head 200 is in its at-rest position and the table14 is in its raised position the left end of lever 378 is in its upwardposition as a` result of the action of the retaining bar 388 on theprevious drop of the table 14. Microswitch 376 is thus in a closedposition. When the cross head 200 goes through its nailing cycle and israised and then depressed, the lug 386 strikes the left end of lever 378at the bottom of the nailing cycle and opens the switch 376. In a mannerto be presently explained the table 14 then drops and the retaining rod388 pulls the right end of lever 378 downwardly to allow microswitch 376to close and remain closed in readiness for another nailing cycle. Thelength of retaining bar 388 is so adjusted that the right end of lever378 is allowed to remain in its raised position until table 14 hasdropped suiciently so that cam 94 no longer depresses microswitches 96,98 and 100.

As may be seen in Figure l the nailing machine is provided with aconventional nailing pedal 480 which, according to the invention, isactuated by means of an air cylinder 402 which is in turn controlled bymeans of a solenoid actuated valve 404.

Referring now to Figure ll there is shown a diagrammatic picturizationof the wiring of the various microswitches and solenoids which controlthe strapping machine of this invention. There it Will be seen that theair motors 264 and 266 are connected by means of air supply pipes 280,281 and 282, 233 to the solenoid valves 284 and 286 respectively. Thesolenoid valves are of the type which open the air valve when thecurrent is on and close the air valve when the current is ott and arefurther of the two-way type in that they are operable either to feed airsupply through conduits 281 and 282 to rotate the air motors in aforward direction or through conduits 283 and 284 to operate the motorsin a reverse direction.

The motors are operated in a forward direction upon the energization ofconnections 406 and 488 which are connected together and to a commonconnection 410. The connection 410 in turn is connected to a switch 412in a timer 414 and the other side of the switch 412 is connected bymeans of a lead 416 to the microswitches 224 and 372 which join one line418 of a source of current supply. A pair of terminals 42() and 422 foroperating the air motors 264 and 266 in the reverse direc- V tion forretracting strapping are connected through microswitches 96 and 98 to acommon connection 424. The lead 424 goes through the microswitch 376 tothe supply line 418. Each of the microswitches 96 and 98 is paralleledby a manual switch 426 and 428 which make it possible to manuallyoperate the air motors 264 and 266 in a reverse direction to manuallyretract strapping from the guides 118 and 120.

The common connections 430 and 432 of solenoids 234 and 286 areconnected through manual switches 434 8 and 436 to the other supply line440. Thus energization of the leads 420 and 422 will cause the airmotors 264 and 266 to feed strapping into the guides 11S and 120 whileenergization of the connections 406 and 488 will cause the air motors toretract strapping from the guides.

The timer 414 is provided with a running winding 442 which is connectedto the lead 416 and to a lead 444 which connects to the supply lead 440.The timer 414 is thus energized as long as microswitches 372 and 224 areclosed and the switch 412 is closed for the predetermined time set onthe timer.

The solenoid 404 which controls the air supply to the piston 402 foractuating the nailing pedal 400, is connected by means of lead 444 tosupply :line 448 and by means of a lead 446 to the microswitch 108. Themicroswitch 160 is in turn connected by means of lead 448 to themicroswitch 376 and thence to the supply line 418. The nailing pedal 400is of the conventional type utilized on nailing machines and will causethe nailing machine to continue to nail as long as it is depressed. Anailing operation is consequently instituted When both microswitches 100and 376 are in an on position and is terminated when switch 376 isopened by the nailing stroke so that only one nailing operation takesplace.

The table lifting cylinders 48 and 50 receive their air supply from asolenoid actuated valve 56. While the solenoid valves 284 and 286 wereof the type which open while the current is on and automatically closewhen the current is cut olf, the solenoid valve 56 is of a differenttype which opens with a pulse of current and remains open even thoughthis current is removed. The valve is subsequently closed by means of apulse of current to a second winding which can only be elective if thecurrent to the first winding has first been removed. The solenoid 56thus has a pair of opening terminals 45t! and 452 and a pair of closingterminals 456 and 458. One opening terminal 450 is connected throughlead 454 to the supply line 440 and the other opening terminal 452 isconnected to microswitch 370 and thence to microswitch 102 and to supplyline 418.

The winding for closing the valves has a pair of terminals 456 and 458,one of which is connected through lead 460 to the supply line 440 andthe other of which is connected through lead 462 to microswitch 374 andthence to supply line 418. The valve is thus opened to cause lifting ofthe table when both microswitches 102 and 370 are closed and thiscircuit is opened to prepare the valve for lowering of the table whenmicroswitch 102 opens in a manner to be presently described. Thelowering operation is caused by a pulse of power to the terminals 456and 458 through the microswitch 374 as that switch is momentarily closedby the cross head 200 at the bottom of the nailing stroke.

The pistons 331 which depress the hold down pins are connected by meansof conduits 361 and 362 to the conduit 82 which leads to the valve 72.An inlet conduit 80 supplies air to the valve 72 which is mechanicallyoperated by the bar 68 on the bracket 64.

The solenoid actuated valve 366 which controls the finger strap guidecylinder 364 is of the same type as solenoid 56, in that the valve opensupon receiving a pulse of current and remains open until a pulse ofcurrent in a further winding causes it to close. The piston 362 is heldin a distended position by the spring 363 as long as the solenoid valveis closed.' The solenoid 366 is provided with a pair of leads 470 and472 for closing the Valve 366 and allowing the spring 363 to distend thepiston 362. The terminals 470 and 472 are connected respectively tosolenoid microswitch 32 and thence to supply line 418 and to lead 474and thence to supply line 440.

The solenoid winding for opening the valve 366 is provided With a pairof terminals 476 and 478 which are respectively connected to themicroswitch 88 and thence to supply line 418 and to lead 480 and thenceto supply line 440. Thus momentary closure of microswitch 32v by meansof a cam section 482 on arm 24 causes the solenoid actuated valve 366 toclose while momentary energization of microswitch 88 by means of nub 84on bracket 64 causes the valve to open to retract the piston 362 and tomove the finger strap guides into position.

The operation of the strapping machine is as follows: Assume that themachine is standing at an at-rest position with strapping in the guide120 but with no box inserted. As a box is pushed into the guides 118 and120 by the: operator it strikes the arms 22 and 24 forcing themoutwardly and causing the cam section 482 on arm 24 to momentarily turnmicroswitch 32 on to thereby send a pulse of power to the closingwinding (terminals 470 and 472) of solenoid actuated valve 366. Thiscauses the valve 366 to close and allows the spring 363 to extend thepiston 362 to remove the finger strap guides 212, 214, 216, 217 and 219from the strapping guides 118 and 120.

As the piston 362 reaches its extended position and the linger strapguides are removed from the tracks, the bracket 356 strikes the buttonon microswitch 370 to close that switch in the raising circuit ofsolenoid actuated valve 56 (terminals 458 and 452). The table at thistime is in its lowered position thereby depressing the button onmicroswitch 102 and closing that switch (as may be seen in Figure l) tocomplete a circuit to the opening winding on solenoid actuated valve 56through lead 454 to terminal 450 and from terminal 452 throughmicroswitches 370 and 102.

As the table rises it opens microswitch 102 so that the solenoidactuated valve 56 is in readiness to receive a pulse in its closingwinding to close the valve and permit the table to drop. The risingtable also carries the bracket 64 upwardly and bar 68 is removed fromthe lever 70 on the valve '72. Spring 78 urges this valve to an openposition, admitting air to the hold down pin cylinders 331 which thenforce levers 334 and pin 228 downwardly as may be seen in Figure 8. Thelowered pins 228 force the strapping 210 downwardly into engagement withthe rising box top, thereby clamping the loose end of the strap to thebox top to permit tensioning by the air motors.

The rising motion of the table further causes microswitches 96, 98, 100to be closed by means of the cam 94, as may be seen in Figures 1 and 2.The microswitches 96 and 98 located beneath the table V14, Figures 1 and2, are in the circuits of the reverse or strap retracting windings ofthe solenoid actuated valves 284 and 286 and are connected in serieswith lever actuated microswitch 376, Figure 10. Microswitch 376 isclosed due to the actions of the retaining bar 388 in lowering the rightend of the lever 378 during the previous fall of the table.

Power is thus applied to solenoids 284 and 286 through microswitches376, 96 and 98 to cause the air motors to withdraw strap from the guides118 and 120 to tension the strap around the box now in position. Thefree end of the strapping 210 is at that time held firm by means of thehold down pins 228 which depress the strapping against the box top. ltwill be seen that the hold down pins exercise some strap anchoringfunction the minute that the box top engages the underside of thestrapping, but that the hold down pins do not exercise a maximum strapanchoring force until the box is near its uppermost position.

Microswitch 100, also in series with microswitch 376, controls thecurrent to the solenoid actuated valve 404 to admit air to the cylinder402 to depress the nailing pedal 400 thereby causing the nailing machineto nail. Depression of nailing pedal 400 causes the nailing beams 192,194, 196 and 198 to first rise and then come downwardly in theconventional manner. During the time that the nailing bars are rising,the air motors 264 and 266 complete the strap tensioning operation sothat the strap is completely tensioned by the time that the nailingbeams commence their downward stroke. Where the 10 source of motivepower is not vsufficiently fast to complete the tensioning operationwith this short period of time it may be necessary to utilize a timer todelay the nailing stroke until after the tensioning is complete.

During the tensioning step the air motors rapidly retract strap from theguides 118 and 120 and then stall when the slack has been removed. Noexcessive power is utilized in this stalled position and no overload orheating of the air motors occurs. While certain types of electricalmotors are available which may be stalledy without any deleteriouseffects, these motors to date have been relatively expensive.` Whilesuch specially designed motors may be used in the strapping machine ofthis invention air motors are to be preferred because of their greaterruggedness, simplicity, durability and low cost. Conventional motorsused in the manner of the invention rapidly overheat and consumeextremely large amounts of power rendering them unsuitable.

As the nailing beams move downwardly in their nailing stroke, the lug262 on nailing beam 194 engages the collar 258 on rod 246 to force theguillotine knife 242 downwardly over the anvil block 204 to sever thestrap 210.

The downward motion of the nailing beams 192 through 198 is caused bythe cross head 200 and as the cross head itself moves downwardly itcloses microswitch 374, best seen in Figure l, to send a momentary pulseof power to the valve closing winding (terminals 456 and 458) ofsolenoid actuated valve 56 to remove the supply of air to the liftingcylinders 48 and 58 and to allow the table 14 to rapidly drop.

The downward movement of the cross head 200 also causes the lug'386,best seen in Figure 10, to depress the left end of lever 378 causing theright end of the lever to rise and open the microswitch 376. This breaksthe supply of current to the solenoid 404 controlling the nailing pedalactuating cylinder 402, and also breaks the supply of current to thereverse windings of the solenoids 284 and 286 so that the air motors 264and 266 come to rest. The size of the lug 386 and the spacing of thelever 378 from the lug 386 must be properly proportioned so that the airto the air motors is cut off prior to the time that the guillotine knife242 severs the strap 210, in order to prevent the air motors fromsnatching the severed strap out of the guides. Momentarily breaking thepower to the solenoid 404 actuating the nailing pedal cylinder 402prevents the nailing machine from cycling more than once.

As has been set out, the downward motion of the cross head 200momentarily closes microswitch 374 sending a flash of current to thesolenoid S6 to cause a rapid dropping of the table 14. As the table 14drops it engages the bent portion 294 of retaining bar 388 to pull theright end of lever 378 downwardly to allow microswitch 376 to closeuntil the next downward movement of the nailing head 200 on the nextnailing cycle.

As the table 14 drops the bar 68 on bracket 64 again engages lever 70 onvalve 72 to shut off the supply of air to the pistons 331 actuating thehold down pins 228. These pins are then raised by the springs 232.

The dropping table also causes nub 84, Figure l, to strike lever tomomentarily close microswitch 88 to send a pulse of current to thesolenoid actuated valve 366 (terminals 476 and 478) to cause the piston362 to move inwardly thereby moving the finger strap guides 342 intoposition in the strapping guides 118 and 120. When the piston 362 is inits retracted position the bracket 356 engages microswitch 372 which isin series with microswitch 224 and is connected in one lead to the timer414.

The microswitch 224, best seen in Figure 4, is normally in a closedposition and is opened by means of lever 218 when the free end of thestrap 210 strikes the lever 218 upon completing its circle around theguides 118 and 120. When the microswitch 372 is closed by means of thefinger strap guides moving into position, the microswitch 224 is alsoclosed since there is no strap in the guides 118 and 120. This energizesthe timer 414 closing the timer switch 412 and this supplies power tothe forward or feed-windings (terminals 406 and 408) of the solenoidactuated valves 284 and 286 for the air motors 264 and 266. The airmotors thereupon feed strapping into the guides 118 and 120 and thestrapping upon completing the circle strikes the lever 218 openingmicroswitch 224 to remove power from the solenoid actuated valves 284and 286 (terminals 406 and`408), thereby stopping the air motors. Themomentum of the motors causes the free end of the strapping 210 to movepast the lever 218 so that the desired overlap of strapping is obtained.Y

The timer 414 is utilized as a safety device to take care of thesituation which might occur were the strapping to jump the tracks 118and 120 and not trip the lever 218 and microswitch 224. In thiscircumstance the air motors would continue to feed strapping until aworkman noticed that something was wrong. The timer 414 maintains theswitch 412 in a closed position for a preset period of time which issoadjusted as to allow the strapping to hit the lever 218. Thus, if thestrapping does jump the track the timer 414 will stop the air motors 264and 266 shortly after the end of the strapping reaches the positionadjacent the lever 218.

The strapping machine is now in its original position and is ready toreceive another box to institute another cycle of operation.

It will be apparent from the foregoing that an inexpensive strappingmachine has been provided which is foolproof and adapted to be appliedto most conventional nailing machines. An air powered strap feed isutilized in a manner to eliminate complex and costly electrical feedsand this same feed is employed to tension the strap through a simplereversal of the motors without the need for expensive and complexclutching arrangements. In addition the strapping is secured by anailing of the overlapped ends without the necessity of complex sealingor tying means and without the necessity of using a strapping guidehaving a gap therein.

While a specic embodiment of the invention has been shown it will beunderstood that this has been by way of illustration only and is not tobe deemed limiting in any sense, the inventionbeing limited solely bythe spirit and terms of the appended claims. In particular theillustrated placement of the various microswitches is illustrative onlyand it will be obvious to those skilled in the art that equivalentplacements would be equally effeclong as they are responsive to the samemovement or occurrence in the cycle of operation. The nailing machinedepicted is also illustrative and any equivalent nailing machine may beutilized.

I claim:

l. In a strapping machine, the combination of; means for supporting theobject to be strapped, a continuous strap guide frame disposed aroundthe object, feeding means for feeding a length of strap into the framewith overlapping portions, said feeding means including a drive Wheelcontinuously rotationally locked to an air motor, means for clampingsaid strap against said object to allow tensioning of said strap, meansfor reversing said air motor to tension said strap and to cause said airmotor to stall, means for nailing said overlapping portions to saidobject, means operable incident to said nailing to sever said strap, andmeans operable incident to said nailing to remove the air supply to saidair motor, said drive wheel remaining in continuous driving engagementwith said strap through an entire cycle of operation.

2. In a strapping machine, the combination of; means for supporting theobject to be strapped, a continuous strap guide frame disposed aroundthe object, said supporting means being vertically movable with respectto said frame, means for feeding a length of strap into the frame withoverlapping portions, said feeding means including a source of motivepower capable of stalling Without overheating, means for causing saidsupporting means to rise, means for clamping said strap against saidobject to allow tensioning of said strap, saidA clamping means beingoperable incident to the rise of said supporting means, means operableincident to said rise of said supporting means for causing said feedingmeans to tension said strap and to cause said source of motive power tostall, means for nailing said overlapping portions to said object, meansoperable incident to said nailing to sever said strap, and meansoperable incident to said nailing to remove the energy supply to saidsource of motive power.

3. In a strapping machine, the combination of; means for supporting theobject to be strapped, a continuous strap guide frame disposed aroundthe object, said supporting means being vertically movable with respectto said frame, means for feeding a length of strap into the frame withoverlapping portions and including an air motor, means for causing saidsupporting means to rise, means for clamping said strap against saidobject to allow tensioning of said strap, said clamping means beingoperable incident to the rise of said supporting means, means operableincident to said rise of said supporting means for causing said feedingmeans to tension said strap and to causesaid air motor to stall, meansfor nailing said overlapping portions to said object, means operableincident to said nailing to sever said strap, and means operableincident to said nailing to remove the air supply to said air motor.

4. In a strapping machine, the combination of; means for supporting theobject to be strapped, an unbroken strap guide frame adjacent saidsupporting means, said supporting means being vertically movable withrespect to said frame, means for feeding a length of strap into theframe with overlapping portions, said feeding means including an airmotor, means for causing said supporting means to rise incident toinsertion of an object into said frame, means for clamping said strapagainst said object to allow tensioning of said strap, said clampingmeans being operable incident to the rise of said supporting means,means operable incident to said rise of said supporting means forcausing said feeding means to tension said strap and to cause said airmotor to stall, means for nailing said overlapping portions to saidobject, means operable incident to said nailing to sever said strap, andmeans operable incident to said nailing to remove the air Supply to saidair motor.

5. in a strapping machine, the combination of; means for supporting theobject to be strapped, an unbroken frame adjacent said supporting means,said supporting means being vertically movable with respect to saidframe, finger strap guides movable into and out of said frame, means formoving said finger strap guides, means for feeding a length of strapinto the frame with overlapped portions incident to movement of saidfinger strap guides into said frame, means causing said finger strapguides to be withdrawn from said frame incident to insertion of anobject into said frame, means causing said supporting means to riseincident to Withdrawal of said finger strap guides, means for clampingsaid strap against said object to allow tensioning of said strap, saidclamping means being operable incident to vthe rise of said supportingmeans,` means operable incident to said rise of said supporting meansfor causing said feeding means to tension said strap, means for nailingsaid overlapping portions to said object, means operable incident tosaid nailing to sever said strap, means operable incident to nailing tocause said supportingmeans to fall, means Y 13 operable incident to saidfall of said supporting means to cause said nger strap guides to moveinto said frame, and means operable incident to said movement of saidlinger strap guides to cause said feeding means to feed strap into saidframe.

6. In a strapping machine, the combination of; means for supporting theobject to be strapped, an unbroken frame adjacent said supporting means,said supporting means being vertically movable with respect to saidframe, nger strap guides movable into and out of said frame, means formoving said finger strap guides, means for feeding a length of strapinto the frame with overlapped portions incident to movement of saidfinger strap guides into said frame, said feeding means including an airmotor, means causing said nger strap guides to be withdrawn from saidframe incident to insertion of an object into said frame, means forclamping said strap against said object to allow tensioning of saidstrap, said clamping means being operable incident to the rise of saidsupporting means, means operable incident to said rise of saidsupporting means for causing said feeding means to tension said strapand to cause said air motor to stall, means for nailing said overlappingportions to said object, means operable incident to said nailing tosever said strap and to cut the air supply to said air motor, meansoperable incident to nailing to cause said supporting means to fall,means operable incident to said fall of said supporting means to causesaid linger strap guides to move into said frame, and means operableincident to said movement of said finger strap guides to cause saidfeeding means to feed strap into said frame.

7. In a strapping machine, the combination of; means for supporting theobject to be strapped, a continuous strap guide frame disposed aroundthe object, said supporting means being vertically movable with respectto said frame, means for feeding a length of strap into the frame withoverlapping portions, means for causing said supporting means to rise,means for clamping said strap against said object to allow tensioning ofsaid strap, said clamping means being operable incident to the rise ofsaid supporting means, means operable incident to said rise of saidsupporting means for causing said feeding means to tension said strap,means for nailing said overlapping portions to said objects, and meansoperable incident to said nailing to sever said strap.

8. In a strapping machine, the combination of; means for supporting theobject to be strapped, an unbroken strap guide frame adjacent saidsupporting means, said supporting means being vertically movable withrespect to said frame, means for feeding a length of strap into theframe with overlapping portions, means for causing said supporting meansto rise incident to insertion of an object into said frame, means forclamping said strap against said object to allow tensioning of saidstrap, said clamping means being operable incident to the rise of said-supporting means, means operable incident to said rise of saidsupporting means for causing said feeding means to tension said strap,means for nailing said overlapping portions to said object, and meansoperable incident to said nailing to sever said strap.

References Cited in the file of this patent UNITED STATES PATENTS1,230,989 Bluege June 26, 1917 1,436,293 Ripley Nov. 21, 1922 1,650,843McChesney Nov. 29, 1927 1,937,675 Twomley Dec. 5, 1933 2,644,944 KQttJuly 14, 1953

